There are various known mechanisms for effecting positive displacement compression and/or expansion in engines, pumps, compressors and other devices. For example, reciprocating engines can employ pistons within cylinders to compress an air fuel mixture and to then output a mechanical force as that air fuel mixture is ignited and expands. Although reciprocating engines and other piston-based positive displacement systems are in wide use, such systems have numerous disadvantages. Piston-based systems can be quite complex and have numerous moving parts. The reciprocating nature of the piston motion can limit the speed at which an engine or other piston-based device can operate. Other disadvantages are well known.
Other types of positive displacement systems utilize rotary motion. For example, some rotary engines and pumps employ one or more vanes coupled to a rotor that turns within a cavity. The vanes maintain sliding contact with the cavity walls and define one or more chambers that vary in volume as the rotor turns. Such designs can have certain limitations, however. For example, maintaining an effective seal between the tip of a vane and a cavity wall can be problematic. Moreover, “chattering” can occur between vanes and the cavity wall. To overcome these and other problems, some designs may include a relatively large number of vanes or otherwise include features that increase complexity.
There remains a need for improved positive displacement rotary systems that can be utilized for internal combustion engines, compressors, pumps and other devices.